Arcade sf2 runs awful on o3ds i'm afraid. You said original sf2 which is world warrior and world warrior only came out on snes aside from the arcade version so that is your best bet. Either that or if you do not mind championship edition/new challengers you can use picodrive for the sega genesis version of the game or hyper fighting/new challengers for snes blargsnes.

Closed source games can't be "ported", they have to be remade. There is no open source Street fighter remake, BUT there is are open source fighting game engines, like paintown, that can be ported to the 3DS.
Kind of related: Here is a list of game clones and remakes that could possibly be ported to the 3DS - http://osgameclones.com/

Closed source games can't be "ported", they have to be remade. There is no open source Street fighter remake, BUT there is are open source fighting game engines, like paintown, that can be ported to the 3DS.
Kind of related: Here is a list of game clones and remakes that could possibly be ported to the 3DS - http://osgameclones.com/

Depends on how well optimized it is, which would depend on the potential coder.

Honestly, how much has been figured out on the 3DS's wireless multiplayer front? Porting something like this would be kind of pointless if you can't play against someone, at least from my understanding of why people like fighting games (not really my thing).